Kerma

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kerma

[′kər·mə]
(nucleonics)
The kinetic energy imparted to charged particles in a unit mass of material by uncharged particles such as neutrons; it may be expressed as joules per kilogram or ergs per gram.

Kerma

 

(ancient Egyptian, Inbu Amenemhet—“Walls of Amenemhet”), a Cushitic settlement south of the third cataract of the Nile, on its right bank (Sudan). Excavations conducted from 1913 to 1916 have revealed a settlement dating from the time of Egypt’s Middle Kingdom (20th-18th centuries B.C.), a necropolis of local rulers buried with their relatives and slaves (as many as 400 persons in one burial); and numerous remains of material culture and art, both of local and Egyptian origin. Kerma lost its importance after Cush was conquered by Egypt (by the 15th century B.C.).

REFERENCES

Katsnel’son, I. S. “Problemy istoricheskogo razvitiia drevneishei Nubii.” Vestnik drevnei istorii, 1948, no. 2.
Reisner, G. A. Excavations at Kerma, vols. 1–2. Cambridge, 1923.
Hintze, F. “Das Kerma-Problem.” Zeitschrift für ägyptische Sprache und Altertumskunde, 1964, vol. 91.
References in periodicals archive ?
On the left is the Radcal IC used to measure incident air kerma from x-ray backscatter systems that were installed at NIST for extended study.
To measure air kerma in a small, swept beam of x rays using a large-volume IC calibrated in a continuously- and fully-illuminated reference beam, one must be able to (1) operate the IC system in an integrating mode, (2) ensure that leakage current is negligible or accounted for over the integration time, (3) fully raster ("paint") the IC as it would be during an operational scan, and (4) account for any incomplete charge collection due to incident fluence rates.
The quantities exposure and air kerma can be related through use of the mean energy expended in a gas per ion pair formed, divided by the elementary charge, W/e, where W is the mean energy expended in air per ion pair formed when the initial kinetic energy of a charged particle is completely dissipated in the air, and e is the elementary charge.
g] is the mean value of g averaged over the distribution of the air kerma with respect to electron energy.
After 7% correction for heel effects at the ion chamber, the chosen reference value of air kerma (exposure) at the center of the imaging plate was 15.
S-values obtained at different values of kVp for constant values of air kerma (exposure) are presented in Figures 2 to 5.
The objective of this proposal was to compare the air kerma calibration coefficients of a reference class chamber determined in reference beams of x rays and gamma rays.
The object was to compare the value of the air kerma calibration coefficient of the chamber determined at the KEBS with the value obtained at the NIST.
Primary standards for the air kerma from photon-emitting radionuclides have been developed by the NBS/NIST as well as by other national metrology institutes.
The National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards (NBS), maintains the primary standards for exposure and air kerma for x rays and gamma rays.
The data shown are converted from dose in mrad to air kerma rate in nGy/h, without correction factors (4) applied.